Antimonide type-II “W” lasers: growth studies and guided-mode leakage into substrate

The lasing characteristics of mid-IR type-II “W” [InAs/GaInSb/InAs/AlAsSb] structures are found to correlate strongly with the growth conditions and low-temperature photoluminescence (PL) properties. The highest PL intensities and narrowest PL lines are obtained when the wafers are grown at ≈480–510°C with mixed interface bonds. A number of structures grown at a non-optimal lower temperature (≈425°C) nonetheless yielded lower lasing thresholds, lower internal losses, and longer Shockley-Read lifetimes than any grown previously on the present Riber 32P MBE system. All of the laser spectra display regularly-spaced multiple peaks that are consistent with periodic modulation of the cavity loss due to mode-leakage into the GaSb substrate.